Be a bit more aggressive in bailing out of this routine. Spotted by

[oota-llvm.git] / lib / Transforms / Scalar / LoopIdiomRecognize.cpp

diff --git a/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index a7bc0e0b43791dede1b56d4ed41b8bf67378135b..a72e288303f78af28086baad11e05ea3abe9fa21 100644 (file)
--- a/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -43,20 +43,20 @@
 
 #define DEBUG_TYPE "loop-idiom"
 #include "llvm/Transforms/Scalar.h"
+#include "llvm/IRBuilder.h"
 #include "llvm/IntrinsicInst.h"
 #include "llvm/Module.h"
+#include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/Analysis/LoopPass.h"
-#include "llvm/Analysis/ScalarEvolutionExpressions.h"
 #include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
 #include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetLibraryInfo.h"
 #include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/IRBuilder.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/ADT/Statistic.h"
 using namespace llvm;
 
 STATISTIC(NumMemSet, "Number of memset's formed from loop stores");
@@ -132,7 +132,8 @@ Pass *llvm::createLoopIdiomPass() { return new LoopIdiomRecognize(); }
 /// and zero out all the operands of this instruction.  If any of them become
 /// dead, delete them and the computation tree that feeds them.
 ///
-static void deleteDeadInstruction(Instruction *I, ScalarEvolution &SE) {
+static void deleteDeadInstruction(Instruction *I, ScalarEvolution &SE,
+                                  const TargetLibraryInfo *TLI) {
   SmallVector<Instruction*, 32> NowDeadInsts;
 
   NowDeadInsts.push_back(I);
@@ -153,7 +154,7 @@ static void deleteDeadInstruction(Instruction *I, ScalarEvolution &SE) {
       if (!Op->use_empty()) continue;
 
       if (Instruction *OpI = dyn_cast<Instruction>(Op))
-        if (isInstructionTriviallyDead(OpI))
+        if (isInstructionTriviallyDead(OpI, TLI))
           NowDeadInsts.push_back(OpI);
     }
 
@@ -164,15 +165,21 @@ static void deleteDeadInstruction(Instruction *I, ScalarEvolution &SE) {
 
 /// deleteIfDeadInstruction - If the specified value is a dead instruction,
 /// delete it and any recursively used instructions.
-static void deleteIfDeadInstruction(Value *V, ScalarEvolution &SE) {
+static void deleteIfDeadInstruction(Value *V, ScalarEvolution &SE,
+                                    const TargetLibraryInfo *TLI) {
   if (Instruction *I = dyn_cast<Instruction>(V))
-    if (isInstructionTriviallyDead(I))
-      deleteDeadInstruction(I, SE);
+    if (isInstructionTriviallyDead(I, TLI))
+      deleteDeadInstruction(I, SE, TLI);
 }
 
 bool LoopIdiomRecognize::runOnLoop(Loop *L, LPPassManager &LPM) {
   CurLoop = L;
 
+  // Disable loop idiom recognition if the function's name is a common idiom.
+  StringRef Name = L->getHeader()->getParent()->getName();
+  if (Name == "memset" || Name == "memcpy")
+    return false;
+
   // The trip count of the loop must be analyzable.
   SE = &getAnalysis<ScalarEvolution>();
   if (!SE->hasLoopInvariantBackedgeTakenCount(L))
@@ -262,7 +269,7 @@ bool LoopIdiomRecognize::runOnLoopBlock(BasicBlock *BB, const SCEV *BECount,
 
 /// processLoopStore - See if this store can be promoted to a memset or memcpy.
 bool LoopIdiomRecognize::processLoopStore(StoreInst *SI, const SCEV *BECount) {
-  if (SI->isVolatile()) return false;
+  if (!SI->isSimple()) return false;
 
   Value *StoredVal = SI->getValueOperand();
   Value *StorePtr = SI->getPointerOperand();
@@ -309,7 +316,7 @@ bool LoopIdiomRecognize::processLoopStore(StoreInst *SI, const SCEV *BECount) {
     const SCEVAddRecExpr *LoadEv =
       dyn_cast<SCEVAddRecExpr>(SE->getSCEV(LI->getOperand(0)));
     if (LoadEv && LoadEv->getLoop() == CurLoop && LoadEv->isAffine() &&
-        StoreEv->getOperand(1) == LoadEv->getOperand(1) && !LI->isVolatile())
+        StoreEv->getOperand(1) == LoadEv->getOperand(1) && LI->isSimple())
       if (processLoopStoreOfLoopLoad(SI, StoreSize, StoreEv, LoadEv, BECount))
         return true;
   }
@@ -458,7 +465,7 @@ processLoopStridedStore(Value *DestPtr, unsigned StoreSize,
     SplatValue = 0;
   } else {
     // Otherwise, this isn't an idiom we can transform.  For example, we can't
-    // do anything with a 3-byte store, for example.
+    // do anything with a 3-byte store.
     return false;
   }
 
@@ -485,7 +492,7 @@ processLoopStridedStore(Value *DestPtr, unsigned StoreSize,
                             StoreSize, getAnalysis<AliasAnalysis>(), TheStore)){
     Expander.clear();
     // If we generated new code for the base pointer, clean up.
-    deleteIfDeadInstruction(BasePtr, *SE);
+    deleteIfDeadInstruction(BasePtr, *SE, TLI);
     return false;
   }
 
@@ -493,7 +500,7 @@ processLoopStridedStore(Value *DestPtr, unsigned StoreSize,
 
   // The # stored bytes is (BECount+1)*Size.  Expand the trip count out to
   // pointer size if it isn't already.
-  const Type *IntPtr = TD->getIntPtrType(DestPtr->getContext());
+  Type *IntPtr = TD->getIntPtrType(DestPtr->getContext());
   BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr);
 
   const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1),
@@ -533,7 +540,7 @@ processLoopStridedStore(Value *DestPtr, unsigned StoreSize,
 
   // Okay, the memset has been formed.  Zap the original store and anything that
   // feeds into it.
-  deleteDeadInstruction(TheStore, *SE);
+  deleteDeadInstruction(TheStore, *SE, TLI);
   ++NumMemSet;
   return true;
 }
@@ -574,7 +581,7 @@ processLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize,
                             getAnalysis<AliasAnalysis>(), SI)) {
     Expander.clear();
     // If we generated new code for the base pointer, clean up.
-    deleteIfDeadInstruction(StoreBasePtr, *SE);
+    deleteIfDeadInstruction(StoreBasePtr, *SE, TLI);
     return false;
   }
 
@@ -589,8 +596,8 @@ processLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize,
                             StoreSize, getAnalysis<AliasAnalysis>(), SI)) {
     Expander.clear();
     // If we generated new code for the base pointer, clean up.
-    deleteIfDeadInstruction(LoadBasePtr, *SE);
-    deleteIfDeadInstruction(StoreBasePtr, *SE);
+    deleteIfDeadInstruction(LoadBasePtr, *SE, TLI);
+    deleteIfDeadInstruction(StoreBasePtr, *SE, TLI);
     return false;
   }
 
@@ -599,7 +606,7 @@ processLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize,
 
   // The # stored bytes is (BECount+1)*Size.  Expand the trip count out to
   // pointer size if it isn't already.
-  const Type *IntPtr = TD->getIntPtrType(SI->getContext());
+  Type *IntPtr = TD->getIntPtrType(SI->getContext());
   BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr);
 
   const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1),
@@ -623,7 +630,7 @@ processLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize,
 
   // Okay, the memset has been formed.  Zap the original store and anything that
   // feeds into it.
-  deleteDeadInstruction(SI, *SE);
+  deleteDeadInstruction(SI, *SE, TLI);
   ++NumMemCpy;
   return true;
 }